The present invention relates to rapid methods for detecting microorganisms in products for human consumption or use, and, more particularly, but not by way of limitation, to methods for detecting the presence or absence of fecal coliform bacteria in water sources.
Due to numerous reported cases of waterborne diseases, the U.S. EPA promulgated new regulations requiring more stringent monitoring of the hygienic quality of drinking water in 1991. The problem is the same on a world wide basis. In developing countries, it is estimated that 80% of morbidity and 33% of mortality is due to poor hygienic water quality. The result of this has been a substantial development in the market for rapid methods for detecting the hygienic quality of water.
In spite of the acute and immediate need for rapid monitoring and control of water quality, --only minor improvements have been achieved since the introduction of the "Bacterium Coli" as an indicator 70 years ago. Current methodology of the detection of the "coliform group" still generally requires 24-48 hours incubation.
It is evident that industries (water, food, beverage, drug, and energy, for example) which are dependant on using or delivering a safe water quality, require quick response to hygienic variations, so that immediate actions can be taken.
Other market areas are armed forces which need continuous monitoring and verification of safe drinking water quality and protection against bacteriological warfare, both regarding war and natural disaster situations. This is especially critical for military field operations, or civil emergency situations where military personnel are responsible for public health.
Market surveys show that the following market volumes exist for the drinking water industry;
Scandinavia: 650 to 850 000 tests per annum; PA1 EEC: 6 000 to 8 000 000 tests per annum; PA1 World wide: up to 20 000 000 tests per annum.
Market volumes may increase by improved technology, and due to the increased focus on internal quality control in the water industry.
Standard methods for assessing the hygienic quality of water, using either membrane filtration (MF) or Most Probable Number (MPN) techniques, require 24 to 72 hours to complete. It is recognized that the elapsed time is far too long to warn of substandard quality and circumvent debilitating or life-threatening diseases.
According to the reference Standard Methods (American Public Health Association, 1989, Standard Methods for the Examination of Water and Wastewater, 17th ed., American Public Health Association, Washington, D.C.) there are a number of rapid methods based upon different principles of detection. The methods generally, however, either lack sensitivity, or require such a long time that the possibility for truly rapid determinations are limited. There is a need therefore for a system which will rapidly detect the presence of fecal coliform bacteria in samples. When used herein, the term "presence" is defined as the occurrence of one or more fecal coliform cells per 100 milliliters of sample.